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Goncalves M.,Federal University of Lavras | Guerreiro M.C.,Federal University of Lavras | Oliveira L.C.A.,Federal University of Minas Gerais | Solar C.,Laboratorio Of Ciencias Of Superficies Y Medios Porosos | And 2 more authors.
Waste and Biomass Valorization | Year: 2013

Activated carbons (ACs) with a highly developed porosity have been prepared from a lignocellulosic precursor (coffee husk) for environmental pollutant adsorption. Characterization results show that these materials exhibit a high amount oxygen groups and high specific surface area with micro mesopores. From SEM results we can see the collapse of large pores at longer activation times. The ACs obtained from coffee husk waste is a promising adsorbent material, with high adsorption capacity for the methylene blue dye (MB). Thus, the use of the coffee husk for AC preparation, with porosity development, showed as a good alternative for the waste transformation. Results also showed that the adsorption of MB by the AC-1/1 was much better than commercial AC from Merck. © 2012 Springer Science+Business Media Dordrecht. Source


Rosmaninho M.G.,Federal University of Minas Gerais | Moura F.C.C.,Federal University of Minas Gerais | Souza L.R.,Federal University of Minas Gerais | Nogueira R.K.,Federal University of Minas Gerais | And 9 more authors.
Applied Catalysis B: Environmental | Year: 2012

In this work, a novel way to indirectly store and produce H 2 from ethanol was investigated using a two-step process based on the reduction of iron oxide followed by oxidation with H 2O. The reduction of different iron oxides, i.e., Fe 2O 3, Fe 3O 4 and FeOOH, with ethanol to produce Fe o was investigated. TPRe (Temperature Programmed Reactions) and Mössbauer and XRD analyses showed that ethanol reduces Fe 2O 3 sequentially to Fe 3O 4 at 350-500°C, to Fe 3O 4/FeO at 500-600°C and finally to Fe o at 700°C. The formed Fe o can then be oxidized by H 2O to produce H 2 and Fe 3O 4, as shown by Mössbauer and XRD analyses. Cyclic experiments showed that iron could be consecutively reduced/oxidized at least 5 times without any significant decrease in H 2 production after the second cycle. However, reactions of Fe 2O 3 with ethanol at higher temperatures, i.e., 800 and 900°C, led to the formation of iron carbide and significant carbon deposition. XPS, SEM, TEM, Raman and TG showed 24-28wt% carbon content, particularly on the surface as nanofibers and as amorphous and graphitic carbon. © 2012. Source

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